Carburetor



April 2, 1935.

S. F. HUNT CARBURETOR Filed Sept. 16, 1932 wuss/ve- MHTEAIHL Ga TORNEYI INVENTOR. 50077 It Hum. BY?- Q EXHHUST 0455s 0,? LUBRICHT/ON OIL 3 Z? o "Patented Apr. 2, .1935- UNITED-3 STATES oaaBUmi'roR Scott F. Hunt, stun] Bend, Ind., assignor to Bendix Aviation Corporation, South Bend, IniL', a corporation of Delaware Application September 16, 1932, Serial No.633,514

carburetors. d

In my Patent No. 1,945,191, January 30, 1934,

5 there is disclosed a carburetor having a pressure responsive choke va1ve, a thermostat opposing opening movement of the valve, and mechanism for opposing the opening movement of the valve only when it is near its closed position, such mech- 1 anism becoming less eifective as the choke valve is moved to its open position. This application discloses various improvements and modifications of the apparatus disclosed in said patent, all. de-' signed to maintain the choke valve substantially closed while .the engine is being cranked, but to permit the choke valve to open, to a degree determined by engine speed and temperature,when the engine begins to fire.

An object of the invention is to provide an automatic choke which functions in accordance with the needs of the, engine and is responsive to the temperature changes.

Another object of the invention is to .provide a choke which is held yieldingly closed, by mechanism which offers itsmaximum resistance to opening at or about the fully closed position of the choke valve.

a choke in which the force tending to close the choke valve is decreased in proportion Other objects and advantages of the invention will be apparent from the following description taken in connection with the appended drawing in which: Figure 1 is a view in elevation of a carburetor having one form of the invention embodied therein;

Figures 2-10 are fragmentary views of other modified forms of therinvention.

The carburetor disclosed in Figure 1 is of the downdraft type, although this is immaterial, and

comprises any suitable arrangement of mixing.

securedto the shaft .20 in such relation as totend to close the choke valve with a force inversely proportional to the temperature.- With this arrangement, the hooked end'of the thermostat may moi (e out of engagement with stop 24 when the engine is fully warmed up. Any other suitable arrangement of the thermostat may be,

used.

A lever 26 secured to shaft 20 and has pivoted to the 4 opening movement of the valve.

(Cl. 123-119) I to its outer end a plate or shoe 28 designed to contact with-a similar plate or shoe 30'supported on a bracket 32 which is fixed to the float chamber or other suitable portion of thecarburetor. The contacting surfaces of shoes 28 and 30 are provided with adhesive material such as gum rubber; so that the choke valve is held shut by the force of adhesion, but upon being opened a slight distance is free from any force tending to close it except the force of the thermostat.

'The construction shown in Figure 2 is similar to that in Figure 1 except that rod 26 supports a vacuum cup 34 at its outer end which is designed to cooperate with a plate 36, of glass or the like, supported adjacent the carburetor on a bracket 38. In this construction, the thermostat, inclosing the choke valve with the aid of gravity, presses the cup 34 into adhesive relation to the plate 36, thereby tending to hold the choke valve closed but releasing it entirely if it is opened beyond a slight angle.

In the construction shown in Figure 3, lever 26 carries a piston 40 which ,is reciprocable in a cylinder 42 connected by a'duct 44 with the interior of the carburetor. The area of piston 40 is so related to the unbalanced segments'of' the choke valve that when suction'is applied to the carbu- 1 Another object of the invention is to provide retor, as during cranking, the force tending to open valve I 8 is nearly, but not quite, counteracted by the suction on piston 40 tending to hold the valve closed. During cranking the force of friction will be sufficient to maintain the parts in equilibrium, but when the engine begins to fire the suction is greatly increased and valve l8 will over- (com the force of piston 40 and move to open position. As soon as this occurs, piston 40 moves intojuxtaposition with a flared mouth portion 46 of the cylinder, so that the suction acting through duct 44 becomes altogether inoperative to restrain the further opening movement of the choke valve. In all of the modifications shown in Figures 1, 2 and 3, the lever 26 is returned, when the engine is stopped, to its original position by gravity and by the force of" the thermostat when .the engine is cold, but this'action may be assisted by a suitable tension spring, if desired.

. In the modification disclosed in Figure 4, the

cylinder 48 is mounted adjacent the choke valve I and is connected by means of a tube 50 to the exhaust pipe or to the lubrication system of the automobile. A piston'52 is connected to the choke valve by means of anoverrunning connection formed by a pin on the choke lever 54 riding in a slot in a link 56. A spring 58 maintains the piston 52 in such position as to hold the choke valve. fully closed, but as soon as the engine fires the increased pressure of the exhaust gases or the lubrication oil will force piston. 52 to the left,

' permitting the choke valve to open;

In the modification of Figure 5, a lever 60 is fixed to the chokeshaft 20, and a tension spring 62 is secured to the end of lever 60 and to the outer wall of the carburetor in such relation as to tend to hold the choke valve closed when it is in closed position. When the valve is opened by the suction developed by the engine when it begins to fire, however, the spring is moved past a dead center position relative to shaft 20, and from then on exerts no force tending to close the choke valve.

In the modification shown in Figure 6, an adjustable stop 64 is supported on a bracket 66 attached to the carburetor, and is connected to the choke lever 68 by means of pivoted toggle levers l0 and 12. The stop 64 is so adjusted with respect to the closed position of the choke valve that levers I0 and 12 return nearly, but not quite, to a position of alignment, and tend to be held in such position by gravity. During cranking, the suction tending to open valve I 8 is insufficient to break the toggle anclpermit the valve to open, since the mechanical advantage is small, but when the engine begins to fire the increased suction is sufficient to break the toggle and when once broken it exerts only a slight force tending to close the choke valve. V

In the modification shown in Figure '7 a hooked lever 14 is secured to the choke shaft 2|], and another hooked member 16 is pivoted to the outer wall of the carburetor in such relation that the two hooks engage when the choke valve is closed. A weight 18 is formed at the lower portion of member 16 to tend to maintain the hooked portion of member 16 in engagement with member 14. This arrangement maintains the choke valve in closed position until the force of suction acting upon it is suflicient to move the hooks past each other,-whereupon the only force tending to maintain the choke valve closed is the force of the thermostat. 4 The disengagement of the hooks upon the starting of the engine is aided by the vibration of the engine,- which tends to cause member 16 to swing about its pivot and thereby disengage the hooks.

In the modification shown in Figure 8, a cylinder is securedto the carburetor and is connected to the intake manifold or carburetor suction by a tube 82. A piston 84 in the cylinder is connected to the choke lever 85 by means of an overrunn'ing connection formed by a pin on lever 85 riding in a slot in a link 86 which is pivoted to the piston. A spring 88 normally holds piston 84 in such position as to retain the choke valve in closed position, but when the engine begins to fire the suction acting through tube 82 draws the piston 84 to the left, thus permitting the valve I8 to open under the influence of carburetor suction.

In the modification disclosed in Figure 9, a lever 90 of ferrous metal is fixed .to shaft 20; and a per-'- manent magnet 92 is flxed'to the carburetorin such relation as to contact with lever 90 when the valve I8 is closed. In this arrangement, it is evident that the maximum force tending to hold the valve closed is exertedwhe'n the parts are in the positions shown in Figure 9, but that when the valve I8 has once been opened-an appreciable distance it is substantially free of the influence of magnet 92. I

In the modification shown in Figure 10, a lever 93 of ferrous or other magnetic metal is secured to the choke valve shaft 20, inoperative relation to an electro-magnet formed by a core member 94 and a second core member 98. An air gap be-- tween the two core members is made adjustable by means of a screw 98 threaded in member 94 to increase or decrease the strength of the magnet.

Assuming that the ignition switch of the automobile is closed, member 94 is. magnetized in such sense as to attract member 93, by a current flowing from the storage battery 99 through the coil I I00. This maintains the choke valve closed while the car is being cranked. When the engine begins to fire, however, current flows from the generator I02 through circuit I04 and coil I06, magnetizing member 94 in a sense opposite to that resulting from coil I00, thereby releasing the member 93 and permitting the choke valve I 8 to open under the influence of carburetor suction.

In all the modifications, it will be understood that'as soon as the choke valve moves out of its closed position it is" substantially freed from the force'tending to hold it closed, but that it remains under the influence of the thermostat, which exerts a resilient force tending to close the valve, the force varying inversely with the temperature at the carburetor. It should also be further noted that if the thermostat is. omitted from any of the modifications shown, the device" bodied in many other forms, and that the inven-' tion is not limited to the modifications disclosed herein except as such limitations are expressed in the following claims.

I claim:

1. Control mechanism for a carburetor comprising a pressure responsive air inlet valve, and

magnetic means constantly opposing opening movement of the valve with a force varying with the position of the valve.

2. Control mechanism for a carburetor for use in automotive vehicles, comprising a pressure responsive air inlet valve, a thermostat influencing the movement of the valve, and magnetic means constantly opposing opening movement of the valve during operation of the vehicle with a force varying with the position of-the valve.

3..Control mechanism for a carburetor comprising a pressure responsive air inlet'valve, and a permanent magnet opposing opening movement of the valve only when the valve is near its closed position.

4. Control mechanism for an internal combustion engine carburetor comprising an air inlet valve, magnetic means opposing opening movement of the valve, and magnetic means rendering the first mentioned magnetic means inoperative when the engine begins to fire.

5. Control mechanism for a carburetor for an internal combustion engine having an ignition circuit; comprising an air inlet valve, and electromagnetic meansenergized by said ignition circuit to urge the valve toward closed position and becoming inoperative when the engine begins to fire. I

6. Control mechanism for a carburetor for an internal combustion engine having an ignition circuit; comprising a pressure responsive air inletvalve, a thermostat influencing the opening of DISCLAIMER 1,996,245.Scott F. Hunt, South Bend, Ind. CARBURETOR. Patent dated April 2, 1935. Disclaimer filed May 26, 1938, by the assignee, Bendix Aviation Corporation.

Hereby enters this disclaimer to claims 1, 2, and 3 of said patent.

[Oflicial Gazette June 21, 1938.] 

